If your preteen or teen is out and stains their underwear or clothing, give them the tip that they can simply place some folded toilet paper over the stain or wrap it around the stain and change your pad or tampon to prevent further leaking. They can also wrap a shirt around their waist if needed. If their underwear is really saturated, they can wash it in the bathroom sink with some cold water and soap — this usually gets most of the blood out. After rinsing in the sink, they can apply some hydrogen peroxide and throw them in the washing machine.